Thats neutral thinking at best. "the world is better off without them" is a very evil line of thought.
No. It isn't. It's a very violent line of thought. It's a very extreme line of thought. But if you haven't noticed paladins are both extreme and violent.
Paladin abilities are all about finding things that the world would be better off without and then killing them with large pointy objects. In a world that needs paladins this is a good thing because that world is so horrific that it IS markedly improved by people doing this.
The chaotic neutral follower of lamasthu is going to leash some unholy spawn of something and something upon the populace. The file clerk of asmodeuous is freeing up resources to run an oppressive empire. They are helping to advance an evil cause. If a paladin chooses to stay their blade and attempt the Unlikely process of conversion that's a legitimate way to be a paladin... but so is winding back up for that second hit.